Nutritive value and multi-mycotoxin occurrence in feeds and milk of dairy cattle

Abstract

Context The contamination of feedstuffs with multi-mycotoxins and their transfer to milk is an important concern because it can affect the health of both animals and humans. Aims This study determined the nutrient composition and quantified the mycotoxins present in dairy feedstuffs and in cow’s milk. Methods Samples of feedstuffs and milk were collected from 11 dairy farms in northern Tunisia for physicochemical composition and mycotoxin analyses. The extraction of mycotoxins was performed by the QuEChERS procedure and the presence of 26 mycotoxins was checked using liquid or gas chromatography with tandem mass spectrometry (LC–MS/MS and GC–MS/MS). Key results Nutrient contents differ among feedstuffs (P < 0.05). The pH values of oat, ryegrass and pulp silages varied from 4.6 to 5.3. Dry-matter (DM) content was highest for concentrate feeds and hay (90% and 86% DM respectively). Crude protein (CP) content was highest in concentrate feeds (15.8% DM). The neutral detergent fibre, acid detergent fibre and acid detergent lignin contents were highest in green grass, hay, and silage. Eight Fusarium mycotoxins, enniatins (ENA1, ENB, ENB1), beauvericine (BEA), HT-2 toxin (HT-2), deoxynivalenol (DON), 15-acetyldeoxynivalenol (15-ADON), Fumonisin B2 (FB2) and one Alternaria mycotoxin tentoxin (TENT) were detected at low concentrations. There was a significant (P < 0.05) difference in the levels of contamination by ENB between the samples of forages and concentrate feeds. The ENs (ENA1, ENB, ENB1) were the most frequently detected combination of mycotoxins. Milk analysis for fat, CP, lactose and dehydrated dry extract averaged 3.49%, 3.10%, 4.71%, and 8.77% respectively; urea concentration was of 34.01 mg/dL, milk pH was 6.5, and a somatic cell count of 1168.63 103 cells/mL was found. Most milk samples (82%) were contaminated with ENB. Conclusions The levels of mycotoxin contamination in feedstuffs and milk were low and do not present a risk for dairy cattle and consumer health. Implications Mycotoxins in feedstuffs and milk should be regularly analysed to make sure that quality and safety standards are met.